PQS SI system units classes

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SI units in PQS

The SI distinction into coherent and incoherent units ¹ allows non-coherent units with conversion factors consisting of powers of 10. e.g kilometers megawatts, while excluding other non-coherent units ( usually legacy units, generally with conversion factors that are not a simple power of 10). PQS clarifies the distinction between allowed and non allowed units by classifying allowed SI units as SI normative units and non allowed units as unit conversions

• Normative units
• Unit conversions

Notes

• [1] The SI system identifies 2 classes of unit, coherent units and non-coherent units . The SI also acknowledges other units outside the SI which are associated with SI units by means of conversion factors, which are also non coherent units .

  Coherent units

  Coherent units consist entirely of some product of SI base_units. There is no use of conversion factors (including integer powers of 10).

  Incoherent units

  Incoherent units are related to coherent units by means of a conversion factor which can convert their numeric value to some value expressed in coherent units.